The Critical Behaviors And Magnetic Properties Of Ferromagnetic Material Based On Bond Dilution And Random Crystal Field Blume-Emery-Griffiths Model

This paper discusses the critical behaviors and magnetic properties of the spin-1 bond dilution and random crystal field Blume-Emery-Griffiths (BEG) model, which is considered on simple cubic lattice within the frame of the effective field theory (EFT). The competition of bond dilution, random mixed (±) crystal field and ratioαconstructs rich and interesting phase diagrams. The system is of two disorder distributions of bond dilution and random crystal field at the same time. The obtained phase diagrams show that there is first-order phase zone by decided of double tricritical points on second-order line. The first-order phase zone shall enlarge with increasing of bond dilution concentration. Two different random behaviors of crystal field affect strongly first-order phase zone and reentrant phase transition. When some disorder conditions are satisfied, there is the tricritical point (TCP) and the desert zone of phase transition with positive ratioαin T ? D plane. Transition lines display single TCP or double TCPs with different random crystal field concentration for strong bond dilution. For negative ratioα, there is always not the TCP for all ranges of bond dilution and random crystal field concentration, while the desert zone of phase transition has an apparent expansion. Bond dilution concentration can further reduce the range of the first-order phase transition. But the re-entrant phase transition was significantly stronger with increasing of ratioα. In the presence of magnetic field, the common action of bond dilution and random crystal field leads to the exhibition of an irregular initial magnetization curve. Under certain condition, the curves appear firstly magnetic platform and tend to saturation magnetism with l =+0.5. Corresponding to the susceptibility curves appear double peak behaviors. On the other hand, some new phenomena have been presented in M ? T plane. Whenα<-1, the phase diagrams present both staggered quadrupolar-paramagnetic and ferromagnetic-paramagnetic phase boundaries, separated by a bicritical point. Moreover, we can find the co-existence of ferromagnetic phase and staggered quadrupolar phase in a certain range of random crystal field concentration.